On Sunday, WhatsApp founder Jan Koum issued a statement placing the blame on a network router.

"We are sorry about the downtime," Koum said in the statement sent to Reuters. "It has been our longest and biggest outage in years. It was caused by a network router fault which cascaded into our servers. We worked with our service provider on resolving the issue and making sure it will not happen again."

About the author

Journalist, software trainer, and Web developer Lance Whitney writes columns and reviews for CNET, Computer Shopper, Microsoft TechNet, and other technology sites. His first book, "Windows 8 Five Minutes at a Time," was published by Wiley & Sons in November 2012.
See full bio